Preparation

In a small skillet heat oil over moderately high heat until hot but not smoking and using tongs, fry chipotles, 1 or 2 at a time, turning them, until puffed and just beginning to brown, about 10 seconds. (Do not let chiles burn or recado will be bitter.) Transfer chipotles as fried to a small bowl, letting excess oil drip off. Add boiling water and soak chipotles, tossing occasionally, until soft, about 20 minutes.

Heat a dry comal or flat iron griddle over moderately low heat and pan-roast onion, garlic, and tomatoes, turning them occasionally to ensure even roasting, until browned and soft throughout, 25 to 30 minutes. Discard garlic skins and tomatoes stems.

In a blender or food processor blend chiles, 1/2 cup soaking water, onion, garlic, tomatoes, tamarind pulp, and salt until smooth. (Recado may be made 5 days ahead and chilled, covered.) Makes about 3 1/4 cups.

To make tamarind pulp:
In a small saucepan barely cover tamarind with water and bring to a boil, covered, over moderate heat. Simmer tamarind gently, covered, stirring frequently, until pulp loosens and falls off seeds, about 30 minutes. (If mixture becomes too thick, add more water to keep barely covered.)

Strain mixture through a medium sieve into a bowl, pushing hard with back of a spoon to extract as much pulp as possible. If pulp does not measure about 1 1/2 cups, return solids to pan with water to barely cover and bring to a boil. Strain tamarind again in same manner to extract more pulp. (Tamarind pulp may be made 1 week ahead and chilled, covered.)